1. Field of the Invention
The present invention relates to a magnetic tape device which is simple in structure, which can be economically produced, and in which a tape cassette moving table can be smoothly moved forward and backward.
2. Description of the Related Art
Conventionally, techniques of a magnetic tape device are disclosed in JP-A-8-31064 and the like. An example of such techniques will be described with reference to FIGS. 14 to 16. In this example, a pair of right and left guide plates 3a and 3b stand in parallel on a chassis 2 in a case 1. A plurality of guide rods 5 which protrude from the side faces of a tape cassette moving table 4 placed between the guide plates 3a and 3b are movably passed through substantially L-like guide holes 6 that are opened in the guide plates 3a and 3b, so that the moving table 4 can be moved forward and backward (a and b) between a cassette inserting position A and a cassette placing position B. Rocking levers 8 which are pivotally attached to the guide plates 3a and 3b via pivot shafts 7 so as to be swung forward and backward (c and d) are engaged with the front guide rods 5, respectively. A worm gear 11 which is rotated by a driving source (not shown) meshes with a worm gear 10 which is formed in an outer peripheral face of a center portion of a rotating cam (rotating member) 9 that is rotatably disposed on the rear face of the chassis 2. A clutch gear mechanism 14 is used as an interlocking mechanism through which a bevel gear 12 formed in an upper outer peripheral face of the rotating cam 9 is interlockingly connected to a gear 13 formed in a basal end portion of the rocking lever 8. The reference numeral 15 denotes a top plate which extends between the guide plates 3a and 3b. 
Referring to FIG. 14, 17 denotes movable tape guide posts which pull out a magnetic tape t from a tape cassette T to wind the tape around a head cylinder 18, 19 denotes a full-track erase head, 20 denotes an audio erase head, 21 denotes an audio control head, 22 denotes stationary tape guide posts, 23 denotes a back tension posts, 24 denotes a capstan, and 25 denotes a pinch roller.
In the above-mentioned configuration, under the state where the moving table 4 is on standby at the cassette inserting position A as indicated by the solid line in FIG. 16, the clutch of the gear mechanism 14 is disengaged. When the tape cassette T is inserted through a tape cassette insertion port 1a of the case 1 to the moving table 4, therefore, the moving table 4 is slightly moved backward (b). In response to a detection signal from a detector (not shown) which detects the backward motion b, the clutch of the gear mechanism 14 is set to the engaged state by the driving source via the worm gear 11, the worm gear 10, and the rotating cam 9, and the rotating cam 9 and the rocking levers 8 are integrally interlockingly connected to each other via the gear mechanism 14. Thereafter, when the rocking levers 8 are swung backward (d) by the driving source, the moving table 4 is horizontally moved backward (b) along the guide holes 6, and then vertically lowered to be placed at the cassette placing position B (see the phantom line in FIG. 16). The magnetic tape t is then pulled out from the tape cassette T (see the phantom line in FIG. 14), and subjected to a process such as replay.
When an eject button (not shown) is pressed, the rocking levers 8 are swung forward (c) in response to an eject signal by the driving source via the gear mechanism 14 and the like. As a result, the moving table 4 at the cassette placing position B is vertically lifted along the guide holes 6, and then moved horizontally forward (a) to the cassette inserting position A, so that the tape cassette T is ejected (see the solid line in FIG. 16).
The above-mentioned configuration has drawbacks that the clutch gear mechanism 14 through which the rotating cam 9 is interlockingly connected to the rocking levers 8 is complicated in structure and its production cost is high, and that backlash of the gear mechanism 14 causes the forward and backward motions a and b of the moving table 4 to become unstable.
In view of the drawbacks, it is an object of the invention to provide a magnetic tape device which is simple in structure, which can be economically produced, and in which a tape cassette moving table can be smoothly moved forward and backward.
In order to attain the object, according to a first aspect of the invention, in a magnetic tape device in which a tape cassette moving table is placed between a pair of right and left guide plates to be movable forward and backward, a rocking lever which is engaged with the moving table and a rotating member which is forward and reversely rotated by a driving source are interlockingly connected to each other via an interlocking mechanism, and the rocking lever is swung by the driving source via the rotating member and the interlocking mechanism to move the moving table forward and backward between a cassette inserting position and a cassette placing position, the interlocking mechanism has a slide plate configured by: a slide plate body which is placed to be slidable along one of the guide plates; and a bent piece which is bent into a substantially L-like shape from a lower edge of the slide plate body to elongate toward the rotating member, a rack which is engaged with a pinion formed on the rotating member is formed on the bent piece, an engaging hole which is to be engaged with an engaging pin protruding from the rocking lever is opened in the slide plate body, a lock lever which is engageable with the engaging pin is pivotally attached to the slide plate body, the rocking lever is backward swung to backward move the moving table toward the cassette placing position by backward sliding the slide plate to cause a peripheral portion of the engaging hole to be engaged with the engaging pin, and the rocking lever is forward swung to forward move the moving table toward the cassette inserting position by forward sliding the slide plate to cause the lock lever to be engaged with the engaging pin.
According to this configuration, the slide plate is used as an interlocking mechanism through which the rotating member is interlockingly connected to the rocking lever. The slide plate can be easily mass-produced simply by bending a steel plate into a substantially L-like shape to form the slide plate body and a bent piece, and forming a rack or the like on the bent piece. Therefore, the production cost is low. Since, unlike a gear mechanism which is conventionally used as an interlocking mechanism, backlash is not caused in the slide plate, the tape cassette moving table can be smoothly moved forward and backward via the rocking lever by sliding forward and backward the slide plate. By the simple structure in which the engaging hole which is opened in the slide plate body is engaged with the engaging pin protruding from the rocking lever, therefore, the moving table can be surely backward moved toward the cassette placing position via the rocking lever, with being interlocked with the backward sliding of the slide plate. Furthermore, by the simple structure in which the lock lever which is pivotally attached to the slide plate body is engaged with the engaging pin, the moving table can be surely forward moved toward the cassette inserting position via the rocking lever, with being interlocked with the forward sliding of the slide plate.
According to a second aspect of the invention, in a magnetic tape device in which a tape cassette moving table is placed between a pair of right and left guide plates to be movable forward and backward, a rocking lever which is engaged with the moving table and a rotating member which is forward and reversely rotated by a driving source are interlockingly connected to each other via an interlocking mechanism, and the rocking lever is swung by the driving source via the rotating member and the interlocking mechanism to move the moving table forward and backward between a cassette inserting position and a cassette placing position, the interlocking mechanism has a slide plate which is placed to be slidable along one of the guide plates, and which is to be engaged respectively with the rotating member and the rocking lever.
According to this configuration, the slide plate is used as an interlocking mechanism through which the rotating member is interlockingly connected to the rocking lever. The slide plate can be economically produced from a steel plate, and hence the production cost is low. Unlike a gear mechanism which is conventionally used as an interlocking mechanism, backlash is not caused in the slide plate. Therefore, the tape cassette moving table can be smoothly moved forward and backward by sliding forward and backward the slide plate.
According to a third aspect of the invention, in the second aspect of the invention, the slide plate is configured by: a slide plate body which is placed along the guide plate; and a bent piece which is bent into a substantially L-like shape from a lower edge of the slide plate body to elongate toward the rotating member, and a rack which is engaged with a pinion formed on the rotating member is formed on the bent piece.
According to this configuration, the slide plate can be economically mass-produced simply by bending a steel plate into a substantially L-like shape to form the slide plate body and the bent piece, and forming the rack on the bent piece.
According to a fourth aspect of the invention, in the third aspect of the invention, a slit which elongates along forward and backward directions is formed at a predetermined position in the slide plate body, a support piece which protrudes from the guide plate is passed through the slit, and a retaining portion which abuts against an outer side face of the slide plate body is disposed in a tip end portion of the support piece.
According to this configuration, the slide plate can be supported so as not to be vertically moved, by passing the support piece protruding from the guide plate through the slit of the slide plate body, and the slide plate can be supported so as not to be separated from the guide plate, by causing the retaining portion disposed in the tip end portion of the support piece to abut against the outer side face of the slide plate body.
According to a fifth aspect of the invention, in the third aspect of the invention, a recessed groove which is longitudinally formed in the bent piece is movably engaged with a lower edge portion of the guide plate.
According to this configuration, since the recessed groove which is longitudinally formed in the bent piece is movably engaged with a lower edge portion of the guide plate, the slide plate can be surely slid along the guide plate under the state where the slide plate is supported so as not to be accidentally moved in vertical and lateral directions.
According to a sixth aspect of the invention, in any one of the second to fifth aspects of the invention, an engaging hole which is to be engaged with an engaging pin protruding from the rocking lever is opened in the slide plate body, and the rocking lever is backward swung to backward move the moving table toward the cassette placing position by backward sliding the slide plate to cause a peripheral portion of the engaging hole to be engaged with the engaging pin.
According to this configuration, by the simple structure in which the engaging hole which is opened in the slide plate body is engaged with the engaging pin protruding from the rocking lever, the moving table can be surely backward moved toward the cassette placing position via the rocking lever, with being interlocked with the backward sliding of the slide plate.
According to a seventh aspect of the invention, in the sixth aspect of the invention, a lift-preventing portion which, when the moving table is placed at the cassette placing position, abuts against or approaches an upper edge of the engaging pin is formed in the peripheral portion of the engaging hole.
According to this configuration, when the moving table is placed at the cassette placing position, the lift-preventing portion which is formed in the peripheral portion of the engaging hole abuts against or approaches the upper edge of the engaging pin, thereby preventing the moving table from being lifted. Therefore, a magnetic tape can be smoothly loaded from a tape cassette which is set on the moving table, so that a clear image can be replayed.
According to an eighth aspect of the invention, in any one of the second to seventh aspects of the invention, a lock lever which is engageable with the engaging pin is pivotally attached to the slide plate body, a lock groove is formed in a tip end portion of the lock lever, and, under a state where the lock lever is swung and the lock groove is opposed to the engaging pin across a gap of a predetermined distance, the slide plate is forward slid to cause the lock groove to be engaged with the engaging pin, thereby forward swinging the rocking lever to forward move the moving table toward the cassette inserting position.
According to this configuration, under the state where the moving table is placed at the cassette placing position, when the slide plate is forward moved in response to an eject signal, also the lock lever is slid in the same direction, and, in the state before the sliding, the gap of a predetermined distance is formed between the lock groove and the engaging pin, so that a short time lag is produced before the lock groove is engaged with the engaging pin. Because of this time lag, it is possible to operate a door of a tape cassette insertion port opposed to the cassette inserting position so as to be opened in advance to the forward motion of the moving table. In accordance with the forward sliding of the slide plate, the lock groove is then engaged with the engaging pin, whereby the rocking lever is forward swung to forward move the moving table, so that a tape cassette which is set on the moving table can be ejected without colliding against the door.
According to a ninth aspect of the invention, in the eighth aspect of the invention, an engaging spring which urges the lock lever toward the engaging pin is disposed, and a lock canceling piece which, when the moving table is forward moved to the cassette inserting position, is engaged with the lock lever against the engaging spring to separate the lock lever from the engaging pin protrudes from the one guide plate.
According to this configuration, when the moving table is forward moved to the cassette inserting position, the lock lever is engaged with the lock canceling piece, whereby the lock lever is separated from the engaging pin against the engaging spring to cancel the lock. When a tape cassette is to be inserted to the moving table which is on standby at the cassette inserting position, therefore, the moving table is allowed to be backward moved, and the backward motion can be surely detected by a detector. Although the lock lever corresponds in function to the clutch in the conventional art, the lock lever is simpler in structure than the clutch, and can be economically produced.
It is important to emphasize that the combination of the lock lever, the engaging pin, the engaging spring, and the lock canceling piece produces both the functions, or the time lag producing function (the eighth aspect of the invention) and the clutch function (the ninth aspect of the invention). This enables the operations of injecting and ejecting a tape cassette to be smoothly performed.
According to a tenth aspect of the invention, in any one of the first to ninth aspects of the invention, a tip end of a door open lever which is pivotally attached to the one guide plate is engaged with a door of a tape cassette insertion port opposed to the cassette inserting position, an opening pin protrudes from the slide plate to be opposed to the door open lever, and the opening pin is engaged with the door open lever to open the door by forward and backward sliding the slide.
According to this configuration, of course, when, in response to an eject signal, the slide plate is forward slid to forward move the moving table at the cassette placing position, the opening pin protruding from the slide plate is engaged with the door open lever so that the door can be opened. Moreover, even in the case where a trouble occurs and the door cannot be opened, the opening pin can be engaged with the door open lever by backward sliding the slide plate, so that the door can be compulsively opened.